Microsoft has announced that the 'Blue' update for Windows 8 will officially be called Windows 8.1 and that it will be available for free for Windows 8 and Windows RT users. A public preview is expected on June 26, the same day the BUILD developer conference is set to begin.

Microsoft announced on their blog today that the often-rumored Windows 8 ‘Blue’ update will actually be named 8.1, and that the update will be completely free for Windows 8 and Windows RT users. This isn’t dissimilar to the service packs that Windows users have received in the past.

They’ve also mentioned that Windows 8.1 will launch as a public preview on June 26. Regarding the contents of the update, details remain scarce other than the few things that have become known, such as the ability to boot to desktop, and the possibility of the Start menu making a return in some fashion.

Chief Marketing Officer Tami Reller assures us that the goal of the updates to the OS is to “create a richer experience for Windows customers”. She continued on to claim that the update “will help us to deliver the next generation of PCs and tablets with our OEM partners and to deliver the experiences customers— both consumers and businesses alike —need and will just expect moving forward.”

The preview build will be available for Windows 8 and Windows RT, and at the end of the blog post Microsoft continued to reiterate that more information on the 8.1 update will be available in the coming weeks. Microsoft’s BUILD developer conference is also June 26, and they assure us that the timing is not co-incidental. We’ll have to wait until the date draws near before we get any concrete details on what this update entails.